--- /dev/null Thu Jan 01 00:00:00 1970 +0000
+++ b/hotspot/src/share/vm/gc/shared/blockOffsetTable.cpp Wed May 13 15:16:06 2015 +0200
@@ -0,0 +1,796 @@
+/*
+ * Copyright (c) 2000, 2015, Oracle and/or its affiliates. All rights reserved.
+ * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
+ *
+ * This code is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License version 2 only, as
+ * published by the Free Software Foundation.
+ *
+ * This code is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
+ * version 2 for more details (a copy is included in the LICENSE file that
+ * accompanied this code).
+ *
+ * You should have received a copy of the GNU General Public License version
+ * 2 along with this work; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
+ *
+ * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
+ * or visit www.oracle.com if you need additional information or have any
+ * questions.
+ *
+ */
+
+#include "precompiled.hpp"
+#include "gc/shared/blockOffsetTable.inline.hpp"
+#include "gc/shared/collectedHeap.inline.hpp"
+#include "gc/shared/space.inline.hpp"
+#include "memory/iterator.hpp"
+#include "memory/universe.hpp"
+#include "oops/oop.inline.hpp"
+#include "runtime/java.hpp"
+#include "services/memTracker.hpp"
+
+//////////////////////////////////////////////////////////////////////
+// BlockOffsetSharedArray
+//////////////////////////////////////////////////////////////////////
+
+BlockOffsetSharedArray::BlockOffsetSharedArray(MemRegion reserved,
+ size_t init_word_size):
+ _reserved(reserved), _end(NULL)
+{
+ size_t size = compute_size(reserved.word_size());
+ ReservedSpace rs(size);
+ if (!rs.is_reserved()) {
+ vm_exit_during_initialization("Could not reserve enough space for heap offset array");
+ }
+
+ MemTracker::record_virtual_memory_type((address)rs.base(), mtGC);
+
+ if (!_vs.initialize(rs, 0)) {
+ vm_exit_during_initialization("Could not reserve enough space for heap offset array");
+ }
+ _offset_array = (u_char*)_vs.low_boundary();
+ resize(init_word_size);
+ if (TraceBlockOffsetTable) {
+ gclog_or_tty->print_cr("BlockOffsetSharedArray::BlockOffsetSharedArray: ");
+ gclog_or_tty->print_cr(" "
+ " rs.base(): " INTPTR_FORMAT
+ " rs.size(): " INTPTR_FORMAT
+ " rs end(): " INTPTR_FORMAT,
+ p2i(rs.base()), rs.size(), p2i(rs.base() + rs.size()));
+ gclog_or_tty->print_cr(" "
+ " _vs.low_boundary(): " INTPTR_FORMAT
+ " _vs.high_boundary(): " INTPTR_FORMAT,
+ p2i(_vs.low_boundary()),
+ p2i(_vs.high_boundary()));
+ }
+}
+
+void BlockOffsetSharedArray::resize(size_t new_word_size) {
+ assert(new_word_size <= _reserved.word_size(), "Resize larger than reserved");
+ size_t new_size = compute_size(new_word_size);
+ size_t old_size = _vs.committed_size();
+ size_t delta;
+ char* high = _vs.high();
+ _end = _reserved.start() + new_word_size;
+ if (new_size > old_size) {
+ delta = ReservedSpace::page_align_size_up(new_size - old_size);
+ assert(delta > 0, "just checking");
+ if (!_vs.expand_by(delta)) {
+ // Do better than this for Merlin
+ vm_exit_out_of_memory(delta, OOM_MMAP_ERROR, "offset table expansion");
+ }
+ assert(_vs.high() == high + delta, "invalid expansion");
+ } else {
+ delta = ReservedSpace::page_align_size_down(old_size - new_size);
+ if (delta == 0) return;
+ _vs.shrink_by(delta);
+ assert(_vs.high() == high - delta, "invalid expansion");
+ }
+}
+
+bool BlockOffsetSharedArray::is_card_boundary(HeapWord* p) const {
+ assert(p >= _reserved.start(), "just checking");
+ size_t delta = pointer_delta(p, _reserved.start());
+ return (delta & right_n_bits(LogN_words)) == (size_t)NoBits;
+}
+
+
+//////////////////////////////////////////////////////////////////////
+// BlockOffsetArray
+//////////////////////////////////////////////////////////////////////
+
+BlockOffsetArray::BlockOffsetArray(BlockOffsetSharedArray* array,
+ MemRegion mr, bool init_to_zero_) :
+ BlockOffsetTable(mr.start(), mr.end()),
+ _array(array)
+{
+ assert(_bottom <= _end, "arguments out of order");
+ set_init_to_zero(init_to_zero_);
+ if (!init_to_zero_) {
+ // initialize cards to point back to mr.start()
+ set_remainder_to_point_to_start(mr.start() + N_words, mr.end());
+ _array->set_offset_array(0, 0); // set first card to 0
+ }
+}
+
+
+// The arguments follow the normal convention of denoting
+// a right-open interval: [start, end)
+void
+BlockOffsetArray::
+set_remainder_to_point_to_start(HeapWord* start, HeapWord* end, bool reducing) {
+
+ check_reducing_assertion(reducing);
+ if (start >= end) {
+ // The start address is equal to the end address (or to
+ // the right of the end address) so there are not cards
+ // that need to be updated..
+ return;
+ }
+
+ // Write the backskip value for each region.
+ //
+ // offset
+ // card 2nd 3rd
+ // | +- 1st | |
+ // v v v v
+ // +-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-
+ // |x|0|0|0|0|0|0|0|1|1|1|1|1|1| ... |1|1|1|1|2|2|2|2|2|2| ...
+ // +-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-
+ // 11 19 75
+ // 12
+ //
+ // offset card is the card that points to the start of an object
+ // x - offset value of offset card
+ // 1st - start of first logarithmic region
+ // 0 corresponds to logarithmic value N_words + 0 and 2**(3 * 0) = 1
+ // 2nd - start of second logarithmic region
+ // 1 corresponds to logarithmic value N_words + 1 and 2**(3 * 1) = 8
+ // 3rd - start of third logarithmic region
+ // 2 corresponds to logarithmic value N_words + 2 and 2**(3 * 2) = 64
+ //
+ // integer below the block offset entry is an example of
+ // the index of the entry
+ //
+ // Given an address,
+ // Find the index for the address
+ // Find the block offset table entry
+ // Convert the entry to a back slide
+ // (e.g., with today's, offset = 0x81 =>
+ // back slip = 2**(3*(0x81 - N_words)) = 2**3) = 8
+ // Move back N (e.g., 8) entries and repeat with the
+ // value of the new entry
+ //
+ size_t start_card = _array->index_for(start);
+ size_t end_card = _array->index_for(end-1);
+ assert(start ==_array->address_for_index(start_card), "Precondition");
+ assert(end ==_array->address_for_index(end_card)+N_words, "Precondition");
+ set_remainder_to_point_to_start_incl(start_card, end_card, reducing); // closed interval
+}
+
+
+// Unlike the normal convention in this code, the argument here denotes
+// a closed, inclusive interval: [start_card, end_card], cf set_remainder_to_point_to_start()
+// above.
+void
+BlockOffsetArray::set_remainder_to_point_to_start_incl(size_t start_card, size_t end_card, bool reducing) {
+
+ check_reducing_assertion(reducing);
+ if (start_card > end_card) {
+ return;
+ }
+ assert(start_card > _array->index_for(_bottom), "Cannot be first card");
+ assert(_array->offset_array(start_card-1) <= N_words,
+ "Offset card has an unexpected value");
+ size_t start_card_for_region = start_card;
+ u_char offset = max_jubyte;
+ for (int i = 0; i < N_powers; i++) {
+ // -1 so that the the card with the actual offset is counted. Another -1
+ // so that the reach ends in this region and not at the start
+ // of the next.
+ size_t reach = start_card - 1 + (power_to_cards_back(i+1) - 1);
+ offset = N_words + i;
+ if (reach >= end_card) {
+ _array->set_offset_array(start_card_for_region, end_card, offset, reducing);
+ start_card_for_region = reach + 1;
+ break;
+ }
+ _array->set_offset_array(start_card_for_region, reach, offset, reducing);
+ start_card_for_region = reach + 1;
+ }
+ assert(start_card_for_region > end_card, "Sanity check");
+ DEBUG_ONLY(check_all_cards(start_card, end_card);)
+}
+
+// The card-interval [start_card, end_card] is a closed interval; this
+// is an expensive check -- use with care and only under protection of
+// suitable flag.
+void BlockOffsetArray::check_all_cards(size_t start_card, size_t end_card) const {
+
+ if (end_card < start_card) {
+ return;
+ }
+ guarantee(_array->offset_array(start_card) == N_words, "Wrong value in second card");
+ u_char last_entry = N_words;
+ for (size_t c = start_card + 1; c <= end_card; c++ /* yeah! */) {
+ u_char entry = _array->offset_array(c);
+ guarantee(entry >= last_entry, "Monotonicity");
+ if (c - start_card > power_to_cards_back(1)) {
+ guarantee(entry > N_words, "Should be in logarithmic region");
+ }
+ size_t backskip = entry_to_cards_back(entry);
+ size_t landing_card = c - backskip;
+ guarantee(landing_card >= (start_card - 1), "Inv");
+ if (landing_card >= start_card) {
+ guarantee(_array->offset_array(landing_card) <= entry, "Monotonicity");
+ } else {
+ guarantee(landing_card == (start_card - 1), "Tautology");
+ // Note that N_words is the maximum offset value
+ guarantee(_array->offset_array(landing_card) <= N_words, "Offset value");
+ }
+ last_entry = entry; // remember for monotonicity test
+ }
+}
+
+
+void
+BlockOffsetArray::alloc_block(HeapWord* blk_start, HeapWord* blk_end) {
+ assert(blk_start != NULL && blk_end > blk_start,
+ "phantom block");
+ single_block(blk_start, blk_end);
+}
+
+// Action_mark - update the BOT for the block [blk_start, blk_end).
+// Current typical use is for splitting a block.
+// Action_single - udpate the BOT for an allocation.
+// Action_verify - BOT verification.
+void
+BlockOffsetArray::do_block_internal(HeapWord* blk_start,
+ HeapWord* blk_end,
+ Action action, bool reducing) {
+ assert(Universe::heap()->is_in_reserved(blk_start),
+ "reference must be into the heap");
+ assert(Universe::heap()->is_in_reserved(blk_end-1),
+ "limit must be within the heap");
+ // This is optimized to make the test fast, assuming we only rarely
+ // cross boundaries.
+ uintptr_t end_ui = (uintptr_t)(blk_end - 1);
+ uintptr_t start_ui = (uintptr_t)blk_start;
+ // Calculate the last card boundary preceding end of blk
+ intptr_t boundary_before_end = (intptr_t)end_ui;
+ clear_bits(boundary_before_end, right_n_bits(LogN));
+ if (start_ui <= (uintptr_t)boundary_before_end) {
+ // blk starts at or crosses a boundary
+ // Calculate index of card on which blk begins
+ size_t start_index = _array->index_for(blk_start);
+ // Index of card on which blk ends
+ size_t end_index = _array->index_for(blk_end - 1);
+ // Start address of card on which blk begins
+ HeapWord* boundary = _array->address_for_index(start_index);
+ assert(boundary <= blk_start, "blk should start at or after boundary");
+ if (blk_start != boundary) {
+ // blk starts strictly after boundary
+ // adjust card boundary and start_index forward to next card
+ boundary += N_words;
+ start_index++;
+ }
+ assert(start_index <= end_index, "monotonicity of index_for()");
+ assert(boundary <= (HeapWord*)boundary_before_end, "tautology");
+ switch (action) {
+ case Action_mark: {
+ if (init_to_zero()) {
+ _array->set_offset_array(start_index, boundary, blk_start, reducing);
+ break;
+ } // Else fall through to the next case
+ }
+ case Action_single: {
+ _array->set_offset_array(start_index, boundary, blk_start, reducing);
+ // We have finished marking the "offset card". We need to now
+ // mark the subsequent cards that this blk spans.
+ if (start_index < end_index) {
+ HeapWord* rem_st = _array->address_for_index(start_index) + N_words;
+ HeapWord* rem_end = _array->address_for_index(end_index) + N_words;
+ set_remainder_to_point_to_start(rem_st, rem_end, reducing);
+ }
+ break;
+ }
+ case Action_check: {
+ _array->check_offset_array(start_index, boundary, blk_start);
+ // We have finished checking the "offset card". We need to now
+ // check the subsequent cards that this blk spans.
+ check_all_cards(start_index + 1, end_index);
+ break;
+ }
+ default:
+ ShouldNotReachHere();
+ }
+ }
+}
+
+// The range [blk_start, blk_end) represents a single contiguous block
+// of storage; modify the block offset table to represent this
+// information; Right-open interval: [blk_start, blk_end)
+// NOTE: this method does _not_ adjust _unallocated_block.
+void
+BlockOffsetArray::single_block(HeapWord* blk_start,
+ HeapWord* blk_end) {
+ do_block_internal(blk_start, blk_end, Action_single);
+}
+
+void BlockOffsetArray::verify() const {
+ // For each entry in the block offset table, verify that
+ // the entry correctly finds the start of an object at the
+ // first address covered by the block or to the left of that
+ // first address.
+
+ size_t next_index = 1;
+ size_t last_index = last_active_index();
+
+ // Use for debugging. Initialize to NULL to distinguish the
+ // first iteration through the while loop.
+ HeapWord* last_p = NULL;
+ HeapWord* last_start = NULL;
+ oop last_o = NULL;
+
+ while (next_index <= last_index) {
+ // Use an address past the start of the address for
+ // the entry.
+ HeapWord* p = _array->address_for_index(next_index) + 1;
+ if (p >= _end) {
+ // That's all of the allocated block table.
+ return;
+ }
+ // block_start() asserts that start <= p.
+ HeapWord* start = block_start(p);
+ // First check if the start is an allocated block and only
+ // then if it is a valid object.
+ oop o = oop(start);
+ assert(!Universe::is_fully_initialized() ||
+ _sp->is_free_block(start) ||
+ o->is_oop_or_null(), "Bad object was found");
+ next_index++;
+ last_p = p;
+ last_start = start;
+ last_o = o;
+ }
+}
+
+//////////////////////////////////////////////////////////////////////
+// BlockOffsetArrayNonContigSpace
+//////////////////////////////////////////////////////////////////////
+
+// The block [blk_start, blk_end) has been allocated;
+// adjust the block offset table to represent this information;
+// NOTE: Clients of BlockOffsetArrayNonContigSpace: consider using
+// the somewhat more lightweight split_block() or
+// (when init_to_zero()) mark_block() wherever possible.
+// right-open interval: [blk_start, blk_end)
+void
+BlockOffsetArrayNonContigSpace::alloc_block(HeapWord* blk_start,
+ HeapWord* blk_end) {
+ assert(blk_start != NULL && blk_end > blk_start,
+ "phantom block");
+ single_block(blk_start, blk_end);
+ allocated(blk_start, blk_end);
+}
+
+// Adjust BOT to show that a previously whole block has been split
+// into two. We verify the BOT for the first part (prefix) and
+// update the BOT for the second part (suffix).
+// blk is the start of the block
+// blk_size is the size of the original block
+// left_blk_size is the size of the first part of the split
+void BlockOffsetArrayNonContigSpace::split_block(HeapWord* blk,
+ size_t blk_size,
+ size_t left_blk_size) {
+ // Verify that the BOT shows [blk, blk + blk_size) to be one block.
+ verify_single_block(blk, blk_size);
+ // Update the BOT to indicate that [blk + left_blk_size, blk + blk_size)
+ // is one single block.
+ assert(blk_size > 0, "Should be positive");
+ assert(left_blk_size > 0, "Should be positive");
+ assert(left_blk_size < blk_size, "Not a split");
+
+ // Start addresses of prefix block and suffix block.
+ HeapWord* pref_addr = blk;
+ HeapWord* suff_addr = blk + left_blk_size;
+ HeapWord* end_addr = blk + blk_size;
+
+ // Indices for starts of prefix block and suffix block.
+ size_t pref_index = _array->index_for(pref_addr);
+ if (_array->address_for_index(pref_index) != pref_addr) {
+ // pref_addr does not begin pref_index
+ pref_index++;
+ }
+
+ size_t suff_index = _array->index_for(suff_addr);
+ if (_array->address_for_index(suff_index) != suff_addr) {
+ // suff_addr does not begin suff_index
+ suff_index++;
+ }
+
+ // Definition: A block B, denoted [B_start, B_end) __starts__
+ // a card C, denoted [C_start, C_end), where C_start and C_end
+ // are the heap addresses that card C covers, iff
+ // B_start <= C_start < B_end.
+ //
+ // We say that a card C "is started by" a block B, iff
+ // B "starts" C.
+ //
+ // Note that the cardinality of the set of cards {C}
+ // started by a block B can be 0, 1, or more.
+ //
+ // Below, pref_index and suff_index are, respectively, the
+ // first (least) card indices that the prefix and suffix of
+ // the split start; end_index is one more than the index of
+ // the last (greatest) card that blk starts.
+ size_t end_index = _array->index_for(end_addr - 1) + 1;
+
+ // Calculate the # cards that the prefix and suffix affect.
+ size_t num_pref_cards = suff_index - pref_index;
+
+ size_t num_suff_cards = end_index - suff_index;
+ // Change the cards that need changing
+ if (num_suff_cards > 0) {
+ HeapWord* boundary = _array->address_for_index(suff_index);
+ // Set the offset card for suffix block
+ _array->set_offset_array(suff_index, boundary, suff_addr, true /* reducing */);
+ // Change any further cards that need changing in the suffix
+ if (num_pref_cards > 0) {
+ if (num_pref_cards >= num_suff_cards) {
+ // Unilaterally fix all of the suffix cards: closed card
+ // index interval in args below.
+ set_remainder_to_point_to_start_incl(suff_index + 1, end_index - 1, true /* reducing */);
+ } else {
+ // Unilaterally fix the first (num_pref_cards - 1) following
+ // the "offset card" in the suffix block.
+ set_remainder_to_point_to_start_incl(suff_index + 1,
+ suff_index + num_pref_cards - 1, true /* reducing */);
+ // Fix the appropriate cards in the remainder of the
+ // suffix block -- these are the last num_pref_cards
+ // cards in each power block of the "new" range plumbed
+ // from suff_addr.
+ bool more = true;
+ uint i = 1;
+ while (more && (i < N_powers)) {
+ size_t back_by = power_to_cards_back(i);
+ size_t right_index = suff_index + back_by - 1;
+ size_t left_index = right_index - num_pref_cards + 1;
+ if (right_index >= end_index - 1) { // last iteration
+ right_index = end_index - 1;
+ more = false;
+ }
+ if (back_by > num_pref_cards) {
+ // Fill in the remainder of this "power block", if it
+ // is non-null.
+ if (left_index <= right_index) {
+ _array->set_offset_array(left_index, right_index,
+ N_words + i - 1, true /* reducing */);
+ } else {
+ more = false; // we are done
+ }
+ i++;
+ break;
+ }
+ i++;
+ }
+ while (more && (i < N_powers)) {
+ size_t back_by = power_to_cards_back(i);
+ size_t right_index = suff_index + back_by - 1;
+ size_t left_index = right_index - num_pref_cards + 1;
+ if (right_index >= end_index - 1) { // last iteration
+ right_index = end_index - 1;
+ if (left_index > right_index) {
+ break;
+ }
+ more = false;
+ }
+ assert(left_index <= right_index, "Error");
+ _array->set_offset_array(left_index, right_index, N_words + i - 1, true /* reducing */);
+ i++;
+ }
+ }
+ } // else no more cards to fix in suffix
+ } // else nothing needs to be done
+ // Verify that we did the right thing
+ verify_single_block(pref_addr, left_blk_size);
+ verify_single_block(suff_addr, blk_size - left_blk_size);
+}
+
+
+// Mark the BOT such that if [blk_start, blk_end) straddles a card
+// boundary, the card following the first such boundary is marked
+// with the appropriate offset.
+// NOTE: this method does _not_ adjust _unallocated_block or
+// any cards subsequent to the first one.
+void
+BlockOffsetArrayNonContigSpace::mark_block(HeapWord* blk_start,
+ HeapWord* blk_end, bool reducing) {
+ do_block_internal(blk_start, blk_end, Action_mark, reducing);
+}
+
+HeapWord* BlockOffsetArrayNonContigSpace::block_start_unsafe(
+ const void* addr) const {
+ assert(_array->offset_array(0) == 0, "objects can't cross covered areas");
+ assert(_bottom <= addr && addr < _end,
+ "addr must be covered by this Array");
+ // Must read this exactly once because it can be modified by parallel
+ // allocation.
+ HeapWord* ub = _unallocated_block;
+ if (BlockOffsetArrayUseUnallocatedBlock && addr >= ub) {
+ assert(ub < _end, "tautology (see above)");
+ return ub;
+ }
+
+ // Otherwise, find the block start using the table.
+ size_t index = _array->index_for(addr);
+ HeapWord* q = _array->address_for_index(index);
+
+ uint offset = _array->offset_array(index); // Extend u_char to uint.
+ while (offset >= N_words) {
+ // The excess of the offset from N_words indicates a power of Base
+ // to go back by.
+ size_t n_cards_back = entry_to_cards_back(offset);
+ q -= (N_words * n_cards_back);
+ assert(q >= _sp->bottom(),
+ err_msg("q = " PTR_FORMAT " crossed below bottom = " PTR_FORMAT,
+ p2i(q), p2i(_sp->bottom())));
+ assert(q < _sp->end(),
+ err_msg("q = " PTR_FORMAT " crossed above end = " PTR_FORMAT,
+ p2i(q), p2i(_sp->end())));
+ index -= n_cards_back;
+ offset = _array->offset_array(index);
+ }
+ assert(offset < N_words, "offset too large");
+ index--;
+ q -= offset;
+ assert(q >= _sp->bottom(),
+ err_msg("q = " PTR_FORMAT " crossed below bottom = " PTR_FORMAT,
+ p2i(q), p2i(_sp->bottom())));
+ assert(q < _sp->end(),
+ err_msg("q = " PTR_FORMAT " crossed above end = " PTR_FORMAT,
+ p2i(q), p2i(_sp->end())));
+ HeapWord* n = q;
+
+ while (n <= addr) {
+ debug_only(HeapWord* last = q); // for debugging
+ q = n;
+ n += _sp->block_size(n);
+ assert(n > q,
+ err_msg("Looping at n = " PTR_FORMAT " with last = " PTR_FORMAT","
+ " while querying blk_start(" PTR_FORMAT ")"
+ " on _sp = [" PTR_FORMAT "," PTR_FORMAT ")",
+ p2i(n), p2i(last), p2i(addr), p2i(_sp->bottom()), p2i(_sp->end())));
+ }
+ assert(q <= addr,
+ err_msg("wrong order for current (" INTPTR_FORMAT ")" " <= arg (" INTPTR_FORMAT ")",
+ p2i(q), p2i(addr)));
+ assert(addr <= n,
+ err_msg("wrong order for arg (" INTPTR_FORMAT ") <= next (" INTPTR_FORMAT ")",
+ p2i(addr), p2i(n)));
+ return q;
+}
+
+HeapWord* BlockOffsetArrayNonContigSpace::block_start_careful(
+ const void* addr) const {
+ assert(_array->offset_array(0) == 0, "objects can't cross covered areas");
+
+ assert(_bottom <= addr && addr < _end,
+ "addr must be covered by this Array");
+ // Must read this exactly once because it can be modified by parallel
+ // allocation.
+ HeapWord* ub = _unallocated_block;
+ if (BlockOffsetArrayUseUnallocatedBlock && addr >= ub) {
+ assert(ub < _end, "tautology (see above)");
+ return ub;
+ }
+
+ // Otherwise, find the block start using the table, but taking
+ // care (cf block_start_unsafe() above) not to parse any objects/blocks
+ // on the cards themselves.
+ size_t index = _array->index_for(addr);
+ assert(_array->address_for_index(index) == addr,
+ "arg should be start of card");
+
+ HeapWord* q = (HeapWord*)addr;
+ uint offset;
+ do {
+ offset = _array->offset_array(index);
+ if (offset < N_words) {
+ q -= offset;
+ } else {
+ size_t n_cards_back = entry_to_cards_back(offset);
+ q -= (n_cards_back * N_words);
+ index -= n_cards_back;
+ }
+ } while (offset >= N_words);
+ assert(q <= addr, "block start should be to left of arg");
+ return q;
+}
+
+#ifndef PRODUCT
+// Verification & debugging - ensure that the offset table reflects the fact
+// that the block [blk_start, blk_end) or [blk, blk + size) is a
+// single block of storage. NOTE: can't const this because of
+// call to non-const do_block_internal() below.
+void BlockOffsetArrayNonContigSpace::verify_single_block(
+ HeapWord* blk_start, HeapWord* blk_end) {
+ if (VerifyBlockOffsetArray) {
+ do_block_internal(blk_start, blk_end, Action_check);
+ }
+}
+
+void BlockOffsetArrayNonContigSpace::verify_single_block(
+ HeapWord* blk, size_t size) {
+ verify_single_block(blk, blk + size);
+}
+
+// Verify that the given block is before _unallocated_block
+void BlockOffsetArrayNonContigSpace::verify_not_unallocated(
+ HeapWord* blk_start, HeapWord* blk_end) const {
+ if (BlockOffsetArrayUseUnallocatedBlock) {
+ assert(blk_start < blk_end, "Block inconsistency?");
+ assert(blk_end <= _unallocated_block, "_unallocated_block problem");
+ }
+}
+
+void BlockOffsetArrayNonContigSpace::verify_not_unallocated(
+ HeapWord* blk, size_t size) const {
+ verify_not_unallocated(blk, blk + size);
+}
+#endif // PRODUCT
+
+size_t BlockOffsetArrayNonContigSpace::last_active_index() const {
+ if (_unallocated_block == _bottom) {
+ return 0;
+ } else {
+ return _array->index_for(_unallocated_block - 1);
+ }
+}
+
+//////////////////////////////////////////////////////////////////////
+// BlockOffsetArrayContigSpace
+//////////////////////////////////////////////////////////////////////
+
+HeapWord* BlockOffsetArrayContigSpace::block_start_unsafe(const void* addr) const {
+ assert(_array->offset_array(0) == 0, "objects can't cross covered areas");
+
+ // Otherwise, find the block start using the table.
+ assert(_bottom <= addr && addr < _end,
+ "addr must be covered by this Array");
+ size_t index = _array->index_for(addr);
+ // We must make sure that the offset table entry we use is valid. If
+ // "addr" is past the end, start at the last known one and go forward.
+ index = MIN2(index, _next_offset_index-1);
+ HeapWord* q = _array->address_for_index(index);
+
+ uint offset = _array->offset_array(index); // Extend u_char to uint.
+ while (offset > N_words) {
+ // The excess of the offset from N_words indicates a power of Base
+ // to go back by.
+ size_t n_cards_back = entry_to_cards_back(offset);
+ q -= (N_words * n_cards_back);
+ assert(q >= _sp->bottom(), "Went below bottom!");
+ index -= n_cards_back;
+ offset = _array->offset_array(index);
+ }
+ while (offset == N_words) {
+ assert(q >= _sp->bottom(), "Went below bottom!");
+ q -= N_words;
+ index--;
+ offset = _array->offset_array(index);
+ }
+ assert(offset < N_words, "offset too large");
+ q -= offset;
+ HeapWord* n = q;
+
+ while (n <= addr) {
+ debug_only(HeapWord* last = q); // for debugging
+ q = n;
+ n += _sp->block_size(n);
+ }
+ assert(q <= addr, "wrong order for current and arg");
+ assert(addr <= n, "wrong order for arg and next");
+ return q;
+}
+
+//
+// _next_offset_threshold
+// | _next_offset_index
+// v v
+// +-------+-------+-------+-------+-------+
+// | i-1 | i | i+1 | i+2 | i+3 |
+// +-------+-------+-------+-------+-------+
+// ( ^ ]
+// block-start
+//
+
+void BlockOffsetArrayContigSpace::alloc_block_work(HeapWord* blk_start,
+ HeapWord* blk_end) {
+ assert(blk_start != NULL && blk_end > blk_start,
+ "phantom block");
+ assert(blk_end > _next_offset_threshold,
+ "should be past threshold");
+ assert(blk_start <= _next_offset_threshold,
+ "blk_start should be at or before threshold");
+ assert(pointer_delta(_next_offset_threshold, blk_start) <= N_words,
+ "offset should be <= BlockOffsetSharedArray::N");
+ assert(Universe::heap()->is_in_reserved(blk_start),
+ "reference must be into the heap");
+ assert(Universe::heap()->is_in_reserved(blk_end-1),
+ "limit must be within the heap");
+ assert(_next_offset_threshold ==
+ _array->_reserved.start() + _next_offset_index*N_words,
+ "index must agree with threshold");
+
+ debug_only(size_t orig_next_offset_index = _next_offset_index;)
+
+ // Mark the card that holds the offset into the block. Note
+ // that _next_offset_index and _next_offset_threshold are not
+ // updated until the end of this method.
+ _array->set_offset_array(_next_offset_index,
+ _next_offset_threshold,
+ blk_start);
+
+ // We need to now mark the subsequent cards that this blk spans.
+
+ // Index of card on which blk ends.
+ size_t end_index = _array->index_for(blk_end - 1);
+
+ // Are there more cards left to be updated?
+ if (_next_offset_index + 1 <= end_index) {
+ HeapWord* rem_st = _array->address_for_index(_next_offset_index + 1);
+ // Calculate rem_end this way because end_index
+ // may be the last valid index in the covered region.
+ HeapWord* rem_end = _array->address_for_index(end_index) + N_words;
+ set_remainder_to_point_to_start(rem_st, rem_end);
+ }
+
+ // _next_offset_index and _next_offset_threshold updated here.
+ _next_offset_index = end_index + 1;
+ // Calculate _next_offset_threshold this way because end_index
+ // may be the last valid index in the covered region.
+ _next_offset_threshold = _array->address_for_index(end_index) + N_words;
+ assert(_next_offset_threshold >= blk_end, "Incorrect offset threshold");
+
+#ifdef ASSERT
+ // The offset can be 0 if the block starts on a boundary. That
+ // is checked by an assertion above.
+ size_t start_index = _array->index_for(blk_start);
+ HeapWord* boundary = _array->address_for_index(start_index);
+ assert((_array->offset_array(orig_next_offset_index) == 0 &&
+ blk_start == boundary) ||
+ (_array->offset_array(orig_next_offset_index) > 0 &&
+ _array->offset_array(orig_next_offset_index) <= N_words),
+ "offset array should have been set");
+ for (size_t j = orig_next_offset_index + 1; j <= end_index; j++) {
+ assert(_array->offset_array(j) > 0 &&
+ _array->offset_array(j) <= (u_char) (N_words+N_powers-1),
+ "offset array should have been set");
+ }
+#endif
+}
+
+HeapWord* BlockOffsetArrayContigSpace::initialize_threshold() {
+ assert(!Universe::heap()->is_in_reserved(_array->_offset_array),
+ "just checking");
+ _next_offset_index = _array->index_for(_bottom);
+ _next_offset_index++;
+ _next_offset_threshold =
+ _array->address_for_index(_next_offset_index);
+ return _next_offset_threshold;
+}
+
+void BlockOffsetArrayContigSpace::zero_bottom_entry() {
+ assert(!Universe::heap()->is_in_reserved(_array->_offset_array),
+ "just checking");
+ size_t bottom_index = _array->index_for(_bottom);
+ _array->set_offset_array(bottom_index, 0);
+}
+
+size_t BlockOffsetArrayContigSpace::last_active_index() const {
+ return _next_offset_index == 0 ? 0 : _next_offset_index - 1;
+}